In the Linux kernel, the following vulnerability has been resolved: rtc: dev: zero-initialize struct rtc_wkalrm to prevent information leak

In the Linux kernel, the following vulnerability has been resolved:

rtc: dev: zero-initialize struct rtc_wkalrm to prevent information leak

The struct rtc_wkalrm has padding holes after the 'pending' member.
When returned to userspace via the RTC_WKALRM_RD ioctl, uninitialized
kernel stack data residing in these holes may be leaked.

Zero-initialize the struct at declaration to eliminate this information
leak risk.

Fixes smatch warnings:

• drivers/rtc/dev.c:392 rtc_dev_ioctl() warn: check that 'alarm' doesn't
  leak information (struct has a hole after 'pending')